Arrangement for connection and disconnection of hybrid transformers at connection between two- and fourwire lines



1959 A. K. BERGMANN 2,915,590

ARRANGEMENT FOR CONNECTION AND DISCONNECTION OF HYBRID TRANSFORMERS AT CONNECTION BETWEEN 2- AND 4-WIRE LINES Fil I/VVENT'OK films/w A muar Biker/0N firraRA/Ew Dec. 1, 1959 A. K. BERG MANN ARRANGEMENT FOR CONNECTION AND DISCONNECTION OF HYBRID TRANSFORMERS AT CONNECTION BETWEEN 2- AND 4-WIRE LINES Filed Dec. 9, 1957 2 Sheets-Sheet 2 United States Patent 2,915,590 ARRANGEMENT FOR CONNECTION AND DIS- CONNECTION OF HYBRID TRANSFORMERS AT CONNECTION BETWEEN TWO- AND FOUR- WIRE LINES Anders Karlby Bergmann, Hagersten, Sweden, assignor to Telefonaktiebolaget L M Ericsson, Stockholm, Sweden, a corporation of Sweden Application December 9, 1957, Serial No. 701,504 Claims priority, application Sweden December 20, 1956 2 Claims. (Cl. 179-16) The present invention relates to an arrangement for connection and disconnection of hybrid transformers at long distance communications for connection between 2- and 4-wire lines in mixed systems.

It is thereby previously known to divide the selector stage in a two wire part and a four wire part at connection between these two types of lines and to connect these parts by aid of links containing hybrid transformers. This causes, however, certain inconvenience, in that the arrangement will be rather complicated and demands considerable material consumption and with that considerable costs. Another previously known method signifies that the hybrid transformers are placed in the lines and are thereafter connected and disconnected by signals from a register with guidance of the number series. This system lacks rather in adaptability, as it does not allow mixture of as well 2-wire as 4-wire lines in the same transmission path.

The present invention is intended to solve the abovementioned problem in a new way, considerable advantages then being obtained by a simplified construction of the system at the same time as the material consumption will be considerably lower than at previously known designs.

The invention relates thus to an arrangement for connection and disconnection of hybrid transformers at interconnections between 2-Wire and 4-wire lines over an arbitrary number of selector stages and where the hybrid transformers are arranged in the one type of lines, characterized by a relay arrangement being arranged in connection with each hybrid transformer in such a way that at a creation of a connection between two lines of the same type and comprising hybrid transformers a circuit is closed via the operation windings in the relay arrangements of the two lines, whereby these relay arrangements are actuated and a short-circuiting of the hybrid transformers is made, but at a setting up of a connection between two lines of different types the relay arrangement included in the connection remains unactuated and the transformer thereby still in action.

The invention will be further described below in connection to the accompanying drawings where Fig. 1 shows an arrangement according to the invention, where the hybrid transformers are placed in the 4-wire lines and Fig. 2 shows the hybrid transformers placed in the 2-wire lines.

Fig. 1 shows two 4-wire lines with therein placed hybrid transformers T with belonging balances B. The two windings are connected via a selector stage of an arbitrary design. In connection to each hybrid transformer there is a test relay Fil respectively Fill and an operating relay F i2 respectively Fu2. Each test relay has an operation winding 1 respectively 11 and a holding winding 2 respectively 2 There are also contacts 11, 11 and 12, 12 which are closed when the operation winding of the relay is energized. Each operating relay has an operation winding 3, 3 as well as a number of contacts 20-30 respectively 20 --30 When two 4-wire ice lines of the above described type are connected via a selector stage a current will appear through the operation windings of the test relays, as these operation wind: ings are connected to potential sources of different polarity. The circuit thereby formed will go from via the winding 1, the contact 30, the conductor b the contact 30 the winding 1 to Hereby the contacts 11, 12, 11 and 12 will be closed. The contacts 11 and 11 close the holding-circuits 11, 2, respectively 11 2 of the test relays, which holding circuits then are energized as long as the established connection is set up. At closing of the contacts 12 respectively 12 the circuits 12, 3, respectively 12 3 are closed, whereby the operation windings of the operating relays F12 respectively Fu2 are energized and the contacts 20-30 respectively 20 ---30 of these relays are actuated in such a way that the contacts 20, 22, 23, 25, 26, 28 and 30 respectively 20 22 23 25 26 28 and 30 are broken and the rest closed. Hereby the hybrid transformers are disconnected and the connection goes directly via the selector stage and the contacts 21, 21 24, 24 27, 27 and 29, 29 At disconnection of the connection the holding windings of the test relays will be de-energized, the contacts 11, 111 and 12, 12 broken and the windings 3, 3 de-energized, all the contacts of the operating relay then returning to initial-position, which is shown in the figure.

If a 2-wire line shall be connected to a 4-wire line of the above described type this will mean that the conductors a and b are missing on the 2-wire side, which in turn prevents the operation winding of the test relay from leading current. The operating relay and its contacts remain then uninfiuenced and a connection is established, where transmission in the one direction is made via the conductors a and b on the 4-wire side, and a and b on the 2-wire side and in the other direction via the conductors a and b, on the 4-wire side and a and b on the 2-wire side.

Fig. 2 shows an example according to the invention, where the hybrid transformers are situated in the 2-wire lines. The same indications as in Fig. 1 have hereby been used and the same arrangements, which were included there are included in this new figure, and therefore a detailed description seems unnecessary. The only difference in this case is that at connection between two 2-wire lines the two test relays in the two 2-wire lines in question are connected against each other via center taps on the one winding of the transformers, the conductors a and b and the contacts 26, 26 and 28, 28 Hereby the circuit is completed through the operation windings 1, 1 of the test relays, and the contacts 11, 11 and :12, 12 are closed. A holding circuit appears then from 2, 11 to respectively from 2 11 to whereby the contacts 12, 12 are held closed and current flows through the operation windings of the operating relays. Thereby the contacts of the relay are influenced in such a way that the contacts 20, 22, 23, 25, 26 and 28 respectively 20 22 23 25 26 and 28 are broken and the rest of the contacts closed. This means a disconnection of the hybrid transformers and therewith also the conductors a and b and a direct 2-wire connection is established between incoming and outgoing lines via the contacts 21, 21 and the conductor a and the contacts 24, 24 and the conductor b If a 2wire line of this type shall be connected with a 4-wire line the test relay in the 2-wire line will not be connected to any corresponding relay in the 4-wire line, since such an equipment is missing there. Current will therefore not appear in the windings of the test relay, and thus the operating relay will not be influenced. The contacts of this relay will then remain in the positions shown on the drawing and a connection is established, where transmission in the one direction is made between the conductors a and b in the 2-wire line and the conductors a and b in the 4-wire line and in the other direction between the conductors a and b in the Z-wire line and the conductors a and b in the 4-wire line.

1 It appears of the above description that connection automatically can be made between two arbitrary lines, either they are of the same type or of different types. The hybrid transformers will therefore in a simple way be automatically disconnected in the cases when they are not needed, at connection between two lines of the same type, which means a considerable advantage against earlier known connections.

The lines connected to a certain selector stage are often to the greatest part either of 4-wire or 2-wire type and the number of the different types are more seldom approximately equal. From economical point of view it is then very suitable to place the hybrid transformers in the line type which forms the smallest part of the lines connected to the selector stage at application of the present invention.

If the hybrid transformers with their balances are placed in the 4-wire lines the balances must of course be of a special type. If on the other hand they are placed in the 2-wire lines the balances can be individual. This system allows, however, the hybrid transformers to be placed in the 4-wire lines and the balances in the 2-wire lines. It is here also possible to connect certain especially long, amplified 2-wire lines to the selector stage in the 4-wire way.

The invention is of course not restricted to the example of embodiment shown on the drawings but can with reference to the detailed construction be varied within the scope of the invention.

I claim:

1. A circuit system for automatically connecting and disconnecting hybrid transformers in mixed connections of two-wire type and four-wire type lines through selector stages, said system comprising hybrid transformers included in one type of said lines, and relay means for each of said hybrid transformers, each of said relay means including a test relay having an operating coil, a hold coil and switch contacts controlled by said operating coil, circuit means energized upon closing a connection between two lines of the same type of lines and including the hybrid transformers and also including the operating coils of said test relays in series connection to energize said test relays for effecting actuation of the switch contacts thereof, circuit means controlled by the actuation of said test relay contacts for closing an energizing circuit for the coils of said operating relays to actuate the switch contacts thereof, circuit means closed by actuation of the operating relay switch contacts for short-circuiting said hybrid transformers and circuit means controlled by closing a connection between two lines of different types of said lines and controlling the operating coils of said test relays for maintaining the same de-energized and to connect the hybrid transformers.

2. A circuit system according to claim 1 wherein the operating coil of each of said test relays in connected to a center tap of a winding of a respective one of said hybrid transformers.

References Cited in the file of this patent UNITED STATES PATENTS 1,850,593 'Mathes Mar. 22, 1932 FOREIGN PATENTS 487,339 Great Britain June 20, 1938 

